1. Field of the Invention
The invention relates to a method for determining the nitrification effectiveness of activated sludge in an aqueous solution (especially water to be purified, or wastewater) and to an apparatus for performing the method.
2. Description of the Related Art
Analysis of water or wastewater for its ingredients and the adjuvants added in the purification/disposal, with regard to their specific effectiveness, is an unavoidable prerequisite to efficient water purification and wastewater disposal in view of the high quality currently demanded.
In the clarification of wastewater from both private and commercial sources, the (biological) degradation of organic hydrocarbon compounds is an urgent goal. In combination with biological purification, the content of biodegradable substances, as expressed in the biological oxygen demand, is a variable of the same decisive importance as the metabolism of the aerobic bacteria that are essential for the purification.
From German Patent DE 29 51 707 C2, a device for determining the concentration of biodegradable substances in wastewater is known, with which the biological oxygen demand of the wastewater (as a measure for this concentration) is ascertained by way of a comparative measurement of the difference in oxygen concentration at the inlet and outlet of two parallel-operated reactors.
As a consequence of the degradation of the hydrocarbon compounds, especially as a byproduct of bacterial digestion of proteins, nitrogen compounds form (ammonium), which disadvantageously cause eutrofication of groundwater and represent a danger to the fish population. These byproducts must therefore also be eliminated in the course of the wastewater purification. The elimination of the ammonium proceeds in two stages: First, by special microorganisms ("nitrifying bacteria") that breathe oxygen dissolved in the water, ammonium is oxidized ("aerobically") into nitrite and nitrate, and then by other microorganisms (denitrification) under oxygen deficiency conditions, the nitrate is reduced (quasi-"anaerobically") into gaseous nitrogen, which can escape into the atmosphere without being processed further.
The bacteria (nitrifying bacteria)--of the genera Nitrobacter and Nitrosomonas--make difficult demands in terms of nutrients, temperature, pH, and other ambient conditions and in particular are very vulnerable to pollutants. Their effectiveness, which determines the nitrification effectiveness of an activated sludge, must therefore be monitored as continuously as possible, for the sake of closely timed control of the purification process as a function of this important variable, and in particular for the sake of optimizing the factors that are involved in the nitrification effectiveness itself. As a result, there is a need for a method and an apparatus for performing it, with which the metabolism of these bacteria and the nitrification effectiveness determined thereby of an activated sludge can be detected continuously by measuring instruments.
The object of the invention is to disclose such a method and a corresponding apparatus.